This invention relates to a process of fireproofing and the resultant fireproof product. More particularly, it relates to fireproofing with foamed magnesium oxychloride cement.
Fireproofing of porous organic materials such as insulating board, fiberboard, and the like has long been a difficult problem. Most chemicals used for fireproofing are expensive in the amounts required, so that the economies of fiberboard are lost in preparation of the commercial fireproof product. Moreover, many of the materials used for "fireproofing" are in fact simply flame retardants, which resist the spread of flames and extinguish the fire by the release of chlorine gas or other extinguishing material. However, fire retardant and flame retardant materials do not prevent the burning of the organic constituents of the porous substrates. In many cases, smoke still is given off through the burning of the cellulose fibers or other organic materials often with the result that severe smoke damage is still possible even though open flames do not break out.
Materials which have layers of fireproof materials over burnable organic materials, such as gypsum board, also suffer shortcomings. Gypsum board is not suitable for exterior use because of severe sensitivity to water. In addition, the paper backing in gypsum board is burnable.
Materials like asbestos-cement board are fireproof, but they are so expensive and so dense that they have not achieved the wide commercial acceptance possible with low-cost materials.
Magnesium oxychloride cement has been known for many years as a flooring material. However, because of its density and lack of porosity, it has not been widely used in other applications. It has previously been suggested to introduce porosity into magnesium oxychloride cement in U.S. Pat. No. 1,429,451 by the inter-mixing of cork or other light material into the cement and thereafter heating to partially decompose the cork particles. Still, the product of this patent is so dense that it has not achieved acceptance in the building and construction trades for walls, roofing, etc.
It has been suggested to make building boards and roofing material from magnesium oxychloride cement in U.S. Pat. No. 1,372,118 by forming magnesium oxychloride cement in a foraminous support. However, the product obtained is so dense and heavy that its usefulness is limited.
A less dense board is described in U.S. Pat. No. 1,500,207 where a magnesium oxychloride cement surface resembling ornamental stone is coated on fiberboard. However, the cement is only on the surface and fails to thoroughly wet all the fibers in order to render them fireproof.
Porous magnesium oxychloride cement is disclosed in U.S. Pat. No. 1,965,538. However, this patent does not relate to fireproofing of burnable products.
U.S. Pat. No. 2,702,753 relates to a foamed magnesium oxychloride tile having certain other ingredients. However, the magnesium oxychloride is not intended to fireproof other burnable materials.
U.S. Pat. No. 3,050,427 shows the use of fibrous glass in a binder. Of the binders listed in this patent, magnesium oxychloride cement is suggested as a possibility. However, the patent does not relate to fireproofing with foamed magnesium oxychloride cement.